Sewing machine control apparatus

ABSTRACT

A sewing machine control apparatus is adapted to move a needle rod to a predetermined stitching starting point automatically when a stitching operation is performed, even if a fabric holding body holding an article to be stitched is displaced relative to the needle rod. The apparatus is equipped with operating means for generating a signal which displaces the fabric holding body in an X-Y direction, second control means responsive to the signal for controlling drive means to move the fabric holding body starting means for generating a signal which starts a driving source of the sewing machine, third control means for storing a signal indicative of the position of the fabric holding body while constantly revising the signal, and fourth control means for controlling the drive means in response to the start signal in such a manner that the fabric holding body is moved from any position to the stitching starting position.

FIELD OF THE INVENTION

This invention relates to a sewing machine control apparatus whereby aseam of a predetermined shape is formed while a fabric holding bodyholding an article to be stitched is moved horizontally relative to aneedle rod and then halted.

PRIOR ART

The aforementioned type sewing machines include cycle stitch sewingmachines such as lock stitch sewing machines, button hole working sewingmachines, button attaching sewing machines and embroidering sewingmachines. In particular, a recent electronically controlled sewingmachine known in the art is adapted for form a seam of a predeterminedshape by coupling a pair of stepping motors to a fabric holding bodyholding an article to be stitched and controlling the stepping motors onthe basis of information stored on an information storage medium such asa floppy disc. When stitching a pattern A→B→C→D of the kind shown inFIG. 4 by the fabric holding body having coordinate axes X, Y and anorigin O₁, with the conventional electronically controlled sewingmachine the needle is moved from an arbitrary point K to a first needledescent point A through the origin O₁ and then is brought to a stop.However, since the stopping position is decided by such factors as theshape and size of the pattern to be stitched, a drawback is that theneedle occasionally becomes an obstacle to a change or insertion offabric.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a sewing machinecontrol apparatus adapted to move a fabric holding body to a stitchingstarting point automatically relative to a needle rod, even if theposition of the fabric holding body relative to the needle rod ischanged, when the machine performs a stitching operation.

Specifically, in a sewing machine having

a needle rod having a needle secured to a lower end thereof and movableup and down in operative association with a main shaft;

a moving body having a fabric holding body to and from which a fabric iscapable of being attached and detached, the moving body being freelymovably supported on an upper surface of a bed in a plane perpendicularto the direction in which the needle rod moves;

drive means coupled to the moving body in such a manner that the movingbody is moved under electrical control in the plane alongperpendicularly intersecting X and Y axes individually or along aresultant direction;

memory means for successively storing needle descent position data foreach stitching pattern as movement data in the X and Y directions from astitching starting position to a stitching end position;

means for reading the movement data out of the memory means; and

first control means for driving the drive means in relation to the readmovement data;

the present invention provides a sewing machine control apparatuscharacterized by provision of:

operating means for generating a displacement signal which moves themoving body in the X and Y directions;

second control means responsive to the displacement signal forcontrolling the drive means to move the moving body to a desiredposition;

starting means for generating a start signal by a manual operation tostart a driving source of the sewing machine;

third control means for storing a signal indicative of the position ofthe fabric holding body, the position signal being revised at all timesbased on the displacement signal, and fourth control means responding tothe generation of the start signal for controlling the drive means insuch a manner that the moving body is moved from a position having X andY coordinates responsive to the revised position signal to a stitchingstarting position of a stitching pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a lock stitch sewing machine;

FIG. 2 is a block diagram of a control circuit;

FIG. 3 is a flowchart of a CPU control program;

FIG. 4 is a graph showing the positional relationship between a patternand a second origin in the conventional lock stitch sewing machine; and

FIG. 5 is a graph illustrating an operation for positionally adjustingthe second origin with respect to a pattern in the lock stitch sewingmachine of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention will now be described withreference to the drawings. Numeral 1 denotes the main body of a lockstitching sewing machine, 2 a bed, and 3 a needle rod having a needle 4secured to its lower end and moved up and down in operative associationwith a main shaft (not shown). Numeral 5 designates a moving body havinga base end coupled to a pair of stepping motors XM, YM (FIG. 2) so as tobe moved in X and Y directions by an arrangement disclosed in, e.g., thepublication of Japanese Patent Application Laid-Open No. 57-55177, and adistal end to which a generally rectangular fabric holding body 6, whichis capable of holding a fabric, is secured in such a manner that aneedle descent point is situated within the rectangle.

Situated on the front side of the sewing machine body 1 are a startswitch SW, a ready switch RW, and a keyboard KB for designating thepattern to be selected and for entering the enlargement or reductionratio of the pattern, and the like. JSW denotes a jog switch comprisingan up switch S₁, a left switch S₂, a down switch S₃, and a right switchS₄, the operation of which will be described later. These operatingmembers are provided on a control panel 7 detachable from the sewingmachine main body 1. The control panel 7 and main body 1 are connectedby a cord, which is not shown.

Control circuitry will be described next.

In FIG. 2, RAM is a random-access memory into which data can be writtenand from which data can be read at will for temporarily storing datafrom a floppy disc. ROM represents a read-only memory solely forread-out and stores a program shown in FIG. 3. CPU denotes a centralporcessing unit having arithmetic and input/output functions.

XDR, YDR designate drive circuits for the stepping motors XM, YM,respectively, and DR denotes a drive circuit for a motor M coupled tothe main shaft. I/O is an interface circuit of the CPU and allows inputand output of instructions and signals between the CPU and XDR, YDR, DR,SW, RW, KB, JSW.

Though not shown, a unit for reading data from a floppy disc is alsoconnected to the I/O.

Described next will be the flowchart of control executed by the controlcircuitry. In FIG. 3, the first step is to select a pattern and set theenlargement or reduction ratio of the pattern by the keyboard KB inorder to start the program. By doing so, a microcomputer inside thesewing machine reads the corresponding pattern data from the floppydisc, the CPU calculates stitching data for every needle with theenlargement or reduction rate serving as a parameter, and the stitchingdata are successively written into the RAM.

It should be noted that a predetermined second origin O₂ different fromthat of the pattern A-B-C-D shown in FIG. 5 has been previouslyincorporated as position data in the above-mentioned pattern data.

When the writing of one cycle of stitching data in the RAM ends, thefabric holding body 6 is moved from the currently prevailing needleposition K (FIG. 5) to the second origin O₂, which is at a predeterminedposition, through the first origin O₁. The reason for the traversal ofthe first origin O₁ at this time is to pre-correct for any maladjustmentdeveloped by the stepping motors XM, YM.

At the conclusion of the foregoing operation, the values of movementparameters P_(x), P_(y) of the fabric holding body 6 are both reset to"0" and the position of the needle is adjusted by using the jog switchJSW. Specifically, when the up switch S₁ is manipulated, the fabricholding body 6 is moved in the -Y direction by an amount equivalent toone pitch (where one pitch is taken as the travelling distancecorresponding to a specific number of steps of movement made by steppingmotor XM or YM), and the value of P_(y) is incremented by "1". When theleft switch S₂ is manipulated, the fabric holding body 6 is moved in the+X direction by an amount equivalent to one pitch and the value of P_(x)is decremented by "1". When the down switch S₃ is manipulated, thefabric holding body 6 is moved in the +Y direction by an amountequivalent to one pitch and the value of P_(y) is decremented by "1".When the right switch S₄ is manipulated, the fabric holding body 6 ismoved in the -X direction by an amount equivalent to one pitch and thevalue of P_(x) is incremented by "1".

When the input operation made by S₁ through S₄ of the jog switch JSW areconcluded, the values of the parameters P_(x), P_(y) calculated owing tooperation of S₁ through S₄ are added respectively to O_(x), O_(y), whichare the respective X and Y coordinates of the second origin O₂, therebyshifting the coordinate values of the second origin O₂.

Next, it is determined whether the start switch SW has been operated.When the start switch SW is operated, the fabric holding body 6 is movedfrom the coordinates (O_(x), O_(y)) of the displaced second origin to afirst needle descent point (X₁, Y₁) of the pattern and a seam is formedby driving the needle 4 into the fabric while the fabric holding body 6is moved by the stepping motors XM, YM on the basis of plural items ofstitching data (X₁, Y₁) through (X_(n), Y_(n)), which have been writteninto the RAM. Thus, when formation of a seam up to the final needledescent point (X_(n), Y_(n)) of the pattern ends, the thread leadingfrom the fabric to the needle 4 is severed by a thread cutting device(not shown) provided on the lower side of the bed, the needle rod 3 israised and stopped, and the fabric holding body 6 is moved from thefinal needle descent point (X_(n), Y_(n)) to the corrected second origin(O_(x), O.sub. y).

If the ready switch RW is operated at this time, a return is effected tothe pattern selection and pattern enlargement or reduction ratio settingoperation performed by the keyboard KB. If the ready switch SW is notmanipulated, however, the values of O_(x), O_(y) are retained, P_(x),P_(y) are set to 0, and a return is effected to the input operationperformed by the jog switch JSW.

(Operation)

Following the introduction of power to the sewing machine main body 1, afloppy disc storing a variety of pattern data is loaded into the sewingmachine main body 1. The pattern shown in FIG. 5 is selected and anenlargement ratio is set by the keyboard KB. As a result, stitching dataare calculated based on both the set pattern data from the floppy discand the enlargement ratio, and the data are successively stored in theRAM. The coordinates O_(x), O_(y) of the second origin O₂ are alsocalculated at this time. When one cycle of stitching data are thusstored in the RAM in their entirety, the stepping motors XM, YM areoperated to move the fabric holding body 6 from the current needleposition K to the first origin O₁ and then to the second origin O₂(O_(x), O_(y)).

Let us assume here that when it is attempted to mount the fabric in thefabric holder 6, the needle 4 situated at the second origin O₂ contactsthe operator's fingers and impedes the mounting of the fabric.Accordingly, the operator presses, say, the left switch S₂ of the jogswitch JSW several times, whereupon the stepping motor XM is driven tomove the fabric holding body 6 to the right by a pitch equivalent to thenumber of times the switch was pressed. Thus, according to therelationship between the pattern A-B-C-D and the needle 4, the latter ismoved leftward relative to the pattern A-B-C-D and the value of P_(x) isdecremented (P₁) by the number of times the switch is pressed.

Next, the up switch S₁ is pressed, whereupon the needle 4 is movedupward (P₂), relatively, by drive supplied by the stepping motor YM.Next, when the left switch S₂ is pressed, the needle 4 is movedrelatively leftward (P₃), and when the down switch S₃ and right switchS₄ are then pressed sequentially, the relative position of the needle 4moves from P₃ to P₄ and thence to O₃.

Though the position of the second origin O₂ (O_(x), O_(y)) is displacedby these operations, the values of the coordinates (O_(x), O_(y))thereof are updated by O_(x) =O_(x) +P_(x), O_(y) =O_(y) +P_(y) eachtime one of the switches S₁ through S₄ of the jog switch JSW is pressed.In other words, the updated coordinates (O_(x), O_(y)) of the secondorigin O₂ are varified by the CPU at all times.

When O₃ in FIG. 5 is thus set as the position of a satisfactory secondorigin (O_(x), O_(y)), the operator presses the start switch SW. Withthis done, the amount of movement (traverse mode) and the direction ofmovement of the fabric holding body 6 are calculated from thecoordinates (O_(x), O_(y)) of O₃ and the first needle descent point (X₁,Y₁) of the stitching data, the fabric holding body 6 is transported to A(X₁, Y₁) by drive supplied by the stepping motors XM, YM, the steppingmotors XM, YM are driven on the basis of the data in the RAM, and theneedle 4 is driven into the fabric from A (X₁, Y₁) to start thestitching operation.

When seam formation progresses from A (X₁, Y₁) to B then to C and thento D (X_(n), Y_(n)) to end one cycle of stitching, the fabric holdingbody 6 returns from D (X_(n), Y_(n)) to the updated second origin O₃(O_(x), O_(y)).

If one of the switches S₁, S₂ of the jog switch JSW is operated, theposition of the aforementioned second origin (O_(x), O_(y)) can beshifted at any time.

Further, when the ready switch RW is pressed, it becomes possible toselect a new pattern and to set the enlargement or reduction ratio ofthe pattern by operating the keyboard KB.

(Advantages of the Invention)

According to the present invention as set forth above, the position ofthe second origin O₂ can be moved with respect to a pattern by operatingswitches such as the jog switch. Therefore, since the second origin O₂can be moved in accordance with the more skillful arm of the operator,the forming of the shape of the fabric and the configuration of thestitched seam, and the operation of attaching the fabric to anddetaching the fabric from the fabric holding body can be facilitated.

In addition, by incrementing or decrementing the predeterminedparameters P_(x), P_(y) at this time by an amount commensurate with jogswitch operation, the CPU constantly monitors the position of the fabricholding body. Accordingly, no matter what position the fabric holdingbody is moved to by the jog switch, the fabric holding body will bemoved to the first needle descent point immediately at the start ofstitching and distortion in the pattern of the stitched seam will notoccur.

(Other Embodiments)

According to the above-described embodiment, a jog switch is used toeffect movement to the second origin O₂. However, the invention is notlimited to this arrangement, for any switch such as a lever switch ortoggle switch may be employed. Alternatively, it would readily occur toone skilled in the art to forgo provision of the jog switch and modifythe program to enable movement of the second origin O₂ by a specificcombination of numerals entered from the keyboard KB.

Further, the present invention is applicable even if the second originO₂ is not placed at a position different from the pattern, e.g., evenfor patterns where the first needle descent point and O₂ coincide.Moreover, a servomotor, linear stepping motor or the like may be used asthe means for driving the moving body 5.

In addition, the present invention is obviously not limited to lockstitch machines but can be widely applied to cycle sewing machines suchas button attaching sewing machines and button hole sewing machines, toembroidering sewing machines and the like.

While the present invention has been described on the basis of apreferred embodiment thereof, various changes and modifications arepossible without departing from the technical scope thereof. Thus, thepresent invention is to be defined solely by the appended claims andshould not be limited to the above embodiment.

We claim:
 1. In a sewing machine including a needle rod having a needlesecured to a lower end thereof and movable up and down directions inoperative association with a main shaft, a moving body having a fabricholding body to and from which a fabric is capable of being attached anddetached, said moving body being freely supported on an upper surface ofa bed for movement in a plane perpendicular to said direction in whichthe needle rod moves, drive means coupled to said moving body in such amanner that said moving body is moved under electrical control in saidplane along perpendicularly intersecting X and Y axes individually oralong a resultant direction, memory means for successively storingneedle descent position data for each stitching pattern as movement datain the X and Y directions from a stitching starting position to astitching end position and for storing a fixed position in the X and Ydirections as a first origin, means for reading said movement data outof said memory means, and first control means for driving said drivemeans in relation to the read movement data, the improvementcomprising:starting means for generating a start signal by a manualoperation to start a driving source of the sewing machine; manualoperating means for generating a position signal in the X and Ydirections before generation of said start signal; second control meansfor controlling said drive means to move said moving body in response tosaid position signal; third control means for storing a position in theX and Y direction corresponding to said position signal as a secondorigin; and fourth control means for controlling said drive means tomove said moving body to a stitching starting position of said secondorigin in response to said start signal and to return said moving bodyto said second origin after completion of the stitching pattern.